Production of ammonia by synthesis and apparatus therefor



July 27 1926.

H. HARTER fRoDUcTIoN 0F AMMONIA BY SYNTHESIS AND APPARATUS THEREFORFiled 001;. 28, 1925 n w m .m

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l who Patented July 27, 1926.

HANS HARTER, F WRZBURG, GERMANY.

PRODUCTION 0F AMMONIA BY SYNTHESIS AND APPARATUS THIE`]R,E]3OR.`

Application filed October 28, 1925, Serial No. 65,273, and in'GermanyAugust 11, 1925.

It has already been proposed in the production of ammonia fromitselements by means of catalysts to combine the two methods generallyknown as `high-pressure and low-pressure synthesis into one singleprocess and, in this case to directly utilize the reaction heat producedby the high pressure synthesis for the low pressure synthesis. Thiscombined process, however, presents the drawbacks that the w-alls of thecatalytic chambers'under pressure are attacked not I only by theresulting heat but also by the hydrogen gas contained in the andfurther, that the reaction temperature in the low-pressure apparatuscannot be kept sufficiently constant. s

According to my present invention these drawbacks are avoided bydirectly or indirectly transmitting the heat, resulting from thehigh-pressure synthesis, to the low-pressure catalyst by means of thereaction gases themselves. For this purpose the high-pressure chambersas well as the low-pressure ones are provided with insulating cylindersarranged between the catalyst and the walls of the said chambers, and,if desired, also walled surrounding the said walls. These insulatingcylinders are double-walled, and the space between their walls is lilledwith the insulatin material, such as coal gravel, diatomite,Ilriieselguhr, l corundum, tridemite, powdered quartz, silica gel etc.,either in solid or broken or plastic form, whereas the catalyticsubstances may be placed in the hollow space of the inner wall .of theinsulating cylinder. Instead of filling doublesheet-iron cylinders withthe insulating material, these insulating cylinders may also be formedof the, insulating substance itself, for instance of chamotte, quartz,zirconic oxide etc. `By passing the reaction gases through the annularspaces formed by the said insulating cylinders, the walls of the tubesunder pressure are protected against the action of the reaction heat andthe hydrogen; on the other hand, a means is produced for regulating atwill the transmission of the reaction heat-to the lowpressure s stem.This may be effected by suitably choosing the insulating material andthe thickness of the insulating layers. Thus for instance by a layerfofkieselguhr or coal gravel having a thickness of 2% inches, thetemperatures can be easily regulated in such a manner that of the wholereaction heat, for instance, of

gas mixture,

only 30 to 40 per cent l they attain a temperature of 300 to 40004centigrade at most, at which temperature thc noxious action of hydrogenon iron is equal to zero, as is generally known. this protection of thetubes under pressure I need not employ a costly special steel, as forinstance V2A for making the pressure tubes, but I can make them ofordinary Siemens-Martin steel, and in case I employ a special steel thedurability of the tubes is considerably increased.

In carrying out my process I may arrange the high-pressure andlow-pressure apparatus either one within the taposition. In both cases,the high-pressure as well as the low-pressure apparatus may .each beprovided with twoinsulating cylinders arranged in the interior of them.

In order that the invention may be more clearly understood and readilyCarried into eil'ect, it will now be described in detail with referenceto the accompanying diagrammatic. drawings, wherein Figure l is adiagrammatic sectional view, showing a. combined high-pressure andlow-pressure system in juxtaposition connected by a heat exchangingdevice.

Figure 2 is a similar sectional view, showing the high-pressure and thelow-pressure system arranged one within the other.

The same reference letters are used in both igures for correspondingparts.

f Referring first to Fig. l, A isv a partial Owing to longitudinalsection through the high-presl sure contact apparatus, B is asimilarsection through the low-pressure apparatus, and C is a longitudinalsection through the pipes of a heat-exchanger. a indicates the wallproper of the high-pressure tube, and b the wall of low-pressure tube.Two double-walled insulating cylinders c, c are provided in the interiorof both tubes a and b, the insulating material d being indicated bydott-ing. The hollow spaces of the inner insulating cylinders c areshown lilled with catalytic substances e, shown to have the form ofumps.

T e gas mixture will enter into the highother or in juxlne `Winding h ofthe heat exchanger C, and

finally into the condenser On the other hand, the low-pressure gasvmixture coming from the compressor le is passed through the outerwinding Z of the heatv exchanger C in counter-current 'with the hothigh-pressure gasfand is then introduced into the annular space gbetween the outer wall b and the outer insulating cylinderc of thelow-pressure apparatus B. The. further course of the gas mixture isindicated by arrows. The gas passes the annular space ows through thecatalyst e and may tien be conducted to the condenser.

Fig. 2 is a fractional .sectional View simi` lar to`Fig. 1, but showingthe high-pressure apparatus arranged conc'entrically in the center of'the low-pressure apparatus. m is the wall ofgthe-high-pressure tube andn the wall of the low-pressure tube. o, p, g and 7* are thedouble-walled insulating cylinders, e indicates the high-pressure and ethe low-pressure catalyst. The highpressure gas is passed in thedirection of the arrows s, s', s, 3 and the low-presgas in the directionof the arrows t, t', til., til. c I x The low-pressure gas is preheatedin this case inthe annular space u by the heat radiatin from the wall ofthe high-pressure tube. e gas is further heated in the annular space lvby the reaction heat produced in the low-pressure tube, and then reachesthe low-pressure catalyst. Should the heat thus transmitted to thelow-pressure gas not suice, the gas before being passed to thelow-pressure catalyst may be further heated by passing it through theouter winding of a heat exchanger similar to C in Fig. l, the innerwinding of which is passed in counter-current by the hot gases comingfrom the high-pressure tube.

As already mentioned before, in the case illustrated by F ig. 2, thehigh-pressure and the low-pressure apparatus are also provided with twoinsulating cylinders. Thus it will be possible to adapt the reactionheat of the high-pressure system to the reaction temperature which ineach `case will I be peculiar to the low-pressure catalyst. For thispurpose a corresponding thickness of the insulating layernn thehigh-pressure tube is chosen, and furthermore the lowpressure gas may beheated to the desired degree-in addition to the heat radiated by lthehigh-pressure system--by the ammoniaeal high-pressure gases in anexchanger. The

exchanger is disconnected as sbn as the v temperature of thelow-pressure gases tends to surpass the suitable reaction temperature.

As a modification, thevlow-pressure tube In may be jacketed with afurther insulating cylinder c, part of which has been shown broken away.s

Another method of proceeding is to surround the high-pressure apparatuswith a pressure-tube having a greater diameter, and passing the coldgases for the lowpressure system under the pressure required for thissystem, through the annular space between the said tube and thehigh-pressure apparatus, so that the gases absorb the heat radiatingfrom the high-pressure apparatus and convey the same to the low-pressuresystem. In this case also the high-pressure system ma be provided withan insulating cylinder. hus the low-pressure gases wi absorb only theheat flowing through -thc insulating layer to the high-pressure tube,whereas the rest of the reaction heat from the high-pressure system maybe trans \mitted to the preheated low-pressure gases in a heatexchanger.

1. In a combined high-pressure and lowpressure apparatus for producingammonia from its elements by catalysis, the arrangement of theinsulating layers between the catalyst and the walls of thehigh-pressure andthe low-pressure chambers, and means for transmitting adesired quantity of the heat produced 1n the high-pressure system to thelowpressure system.

2. In an apparatus according to claim l, the arrangement of insulatinglayers between two concentric cylinders.

. 3. In an apparatus according to claim l, the combination of thelhigh-pressure'an d ma the low-pressure system with a heat eX- y changerand means for conducting the hot gases resulting from the'high-pressuresystem and the gases to be supplied to the lowpressure system throughthe said exchanger in counter-current.

4. In an apparatus according to claim 1, the arrangement of theinsulating layers in such a manner that spaces are left between the saidlayers and the corresponding wall, and means for conducting the gasesthrough the said spaces.

5. In an apparatus according to claim l, the arrangement of a pluralityof insulating layers between the catalyst and the walls of thehigh-pressure and the low-pressure chambers, spaces being left betweenthe subsequent insulating layers and between the outer insulating layerand the adjacent wall, and means for conducting the gases through thesaid spaces.

t In testimony whereof I aiiix my signaure.

